drm/udl: Use NULL instead of 0 for pointers
drm/udl: Use NULL instead of 0 for pointers

Fixes the following sparse warnings:
drivers/gpu/drm/udl/udl_transfer.c:129:50:
drivers/gpu/drm/udl/udl_transfer.c:130:50:
drivers/gpu/drm/udl/udl_transfer.c:131:45:
drivers/gpu/drm/udl/udl_transfer.c:132:61:
warning: Using plain integer as NULL pointer

Signed-off-by: Sachin Kamat <1c3b1584a6008857f36c03c58f657c0fc16fc09e@linaro.org>
Signed-off-by: Dave Airlie <f2295d84e358395675bc8031be58672073ae065e@redhat.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs